The science and economics of drug discovery has changed with developments in the areas of genomics, combinatorial chemistry and high-throughput screening. The number of targets has increased as a result of genomics while the number of small molecule compounds (samples) has dramatically increased as a result of combinatorial chemistry. This increase in targets and compounds has an exponential effect on the number of tests that need to be performed to increase the likelihood of finding a new chemical entity using high-throughput screening. Microliter amounts of target and sample must suffice for many screening assays, putting pressure on the automation industry to provide new tools to increase throughput, efficiency, and reduce R&D costs. Conventional R&D screening efforts use multiple variations of pipetting to move aliquots of the concentrated liquid sample from storage receptacles, to working receptacles, to dilution receptacles and finally to assay receptacles. This “reformatting” process, or “sample prep.” adds complexity to the overall process, wastes valuable sample or target, and increases time and assay cost.
Disposable pipette tips and non-disposable, cleanable pipetting devices are commonly used for proportioning liquids. Pipette tips and pipetting devices include an input aperture at one end and a placement aperture at the other end for attachment to the pipetting device. The pipetting device often encompasses a piston-cylinder positive displacement mechanism. The pipette tip attaches to the pipetting device through a variety of mechanical connection schemes. A column of air connects the piston-cylinder mechanism to the pipette tip through a fluidic interface. Liquid is aspirated into the pipette tip when the pipette tip's input aperture is submerged in liquid while the piston-cylinder mechanism draws in. The air column and aspirated liquid draw into the pipette tip via a proportioned amount. The liquid is dispensed from the tip by reversing the direction of the piston-cylinder mechanism. The amount of liquid that may be aspirated and dispensed is limited by a number of factors including but not limited to: pipette tip material, pipette tip surface finish, input aperture capillary forces, liquid surface energy, and piston-cylinder mechanism limitations.
Tubes, capillary channels, and plate surfaces make-up categories of devices that are used in many market applications that involve the transfer of fluids. In the drug discovery market, new developments in the area of “chip” based systems involve capillary channels to move fluids through a myriad of systemic processes. In the diagnostic market, tubes and pipetting devices are used to perform a number of liquid tests, all burdened by the limited amount of source liquid vs. the number of tests that are desired to be run against those source liquids.